Apparatuses and methods consistent with exemplary embodiments relate to wiring boards and semiconductor packages including the same, and more particularly, to a wiring board that can improve reliability and a semiconductor package including the same.
In a semiconductor package having a ball grid array (BGA) type structure, since an external connection terminal is surface-arranged, many pins may be provided, a mounting area is not great, and a thermal resistance and an electrical characteristic is superior. For such a reason, to meet an increase of integration of a semiconductor device and an increase of the number of input/output pins, a use of the semiconductor package adopting the BGA type structure is increasing.
A semiconductor package of the BGA type structure is classified into a solder mask defined (SMD) type and a non-solder mask defined (NSMD) type according to a ball land structure. A semiconductor package having an SMD type ball land structure and a semiconductor package having an NSMD type ball land structure are described below.
In the SMD type ball land structure, a wiring board has an upper surface on which a semiconductor chip is mounted and a lower surface facing the upper surface on which a ball land is formed, a solder ball joins a ball land as an external connection terminal, and a solder mask formed on the lower surface of the wiring board covers a part of an edge of the ball land.
In a semiconductor package having the SMD type ball land structure, a connection area of a solder ball is wide and a binding power between a ball land and the solder ball is superior due to a locking effect. However, since a contact area between the ball land and the solder ball is small, a solder joint reliability (SJR) is not good in an electrical characteristic.
In the NSMD type ball land structure, a solder mask is formed to be spaced a predetermined distance apart from a ball land formed on the lower surface of the wiring board.
In a semiconductor package having the NSMD type ball land structure, since the ball land and a solder ball are spaced apart from each other, a contact area between the solder ball and the ball land is great and thereby a solder joint reliability (SJR) is good in an electrical characteristic. However, since a connection area of the solder ball is small, a binding power of the solder ball is low as compared with the SMD type ball land structure.